Injuries to the ureter from blunt trauma occur most often at the ureteropelvic junction. A delayed diagnosis is typical because of the presence of other injuries. Injuries occurring to other parts of the ureter are usually over the transverse processes. The case of a 15-year-old boy with a mid-ureteral contusion from blunt trauma is presented, in whom compression or impaction of the ureter across the L5 vertebra caused edema late and therefore a partial obstruction. Such injuries should be considered when there is delayed abdominal or flank pain, especially in children.